/*
 ** Authored by Timothy Gerard Endres
 ** <mailto:time@gjt.org>  
 ** 
 ** This work has been placed into the public domain.
 ** You may use this work in any way and for any purpose you wish.
 **
 ** THIS SOFTWARE IS PROVIDED AS-IS WITHOUT WARRANTY OF ANY KIND,
 ** NOT EVEN THE IMPLIED WARRANTY OF MERCHANTABILITY. THE AUTHOR
 ** OF THIS SOFTWARE, ASSUMES _NO_ RESPONSIBILITY FOR ANY
 ** CONSEQUENCE RESULTING FROM THE USE, MODIFICATION, OR
 ** REDISTRIBUTION OF THIS SOFTWARE. 
 ** 
 */

package com.myJava.file.archive.tar;

import java.io.File;
import java.io.FilterInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;


/**
 * The TarInputStream reads a UNIX tar archive as an InputStream.
 * methods are provided to position at each successive entry in
 * the archive, and the read each entry as a normal input stream
 * using read().
 *
 * Kerry Menzel <kmenzel@cfl.rr.com> Contributed the code to support
 * file sizes greater than 2GB (longs versus ints).
 *
 *
 * @version $Revision: 1.9 $
 * @author Timothy Gerard Endres, <time@gjt.org>
 * @see TarBuffer
 * @see TarHeader
 * @see TarEntry
 * 
 * <BR>
 * <BR>CAUTION :
 * <BR>This file has been integrated into Areca.
 * <BR>It is has also possibly been adapted to meet Areca's needs. If such modifications has been made, they are described above.
 * <BR>Thanks to the authors for their work.
 *
 */


public
class		TarInputStream
extends		FilterInputStream
{
    protected boolean			debug;
    protected boolean			hasHitEOF;
    
    protected long				entrySize;
    protected long				entryOffset;
    
    protected byte[]			oneBuf;
    protected byte[]			readBuf;
    
    protected TarBuffer			buffer;
    
    protected TarEntry			currEntry;
    
    protected EntryFactory		eFactory;
    
    
    public
    TarInputStream( InputStream is )
    {
        this( is, TarBuffer.DEFAULT_BLKSIZE, TarBuffer.DEFAULT_RCDSIZE );
    }
    
    public
    TarInputStream( InputStream is, int blockSize )
    {
        this( is, blockSize, TarBuffer.DEFAULT_RCDSIZE );
    }
    
    public
    TarInputStream( InputStream is, int blockSize, int recordSize )
    {
        super( is );
        
        this.buffer = new TarBuffer( is, blockSize, recordSize );
        
        this.readBuf = null;
        this.oneBuf = new byte[1];
        this.debug = false;
        this.hasHitEOF = false;
        this.eFactory = null;
    }
    
    /**
     * Sets the debugging flag.
     *
     * @param debugF True to turn on debugging.
     */
    public void
    setDebug( boolean debugF )
    {
        this.debug = debugF;
    }
    
    /**
     * Sets the debugging flag.
     *
     * @param debugF True to turn on debugging.
     */
    public void
    setEntryFactory( EntryFactory factory )
    {
        this.eFactory = factory;
    }
    
    /**
     * Sets the debugging flag in this stream's TarBuffer.
     *
     * @param debugF True to turn on debugging.
     */
    public void
    setBufferDebug( boolean debug )
    {
        this.buffer.setDebug( debug );
    }
    
    /**
     * Closes this stream. Calls the TarBuffer's close() method.
     */
    public void
    close()
    throws IOException
    {
        this.buffer.close();
    }
    
    /**
     * Get the record size being used by this stream's TarBuffer.
     *
     * @return The TarBuffer record size.
     */
    public int
    getRecordSize()
    {
        return this.buffer.getRecordSize();
    }
    
    /**
     * Get the available data that can be read from the current
     * entry in the archive. This does not indicate how much data
     * is left in the entire archive, only in the current entry.
     * This value is determined from the entry's size header field
     * and the amount of data already read from the current entry.
     * 
     *
     * @return The number of available bytes for the current entry.
     */
    public int
    available()
    throws IOException
    {
        return (int)(this.entrySize - this.entryOffset);
    }
    
    /**
     * Skip bytes in the input buffer. This skips bytes in the
     * current entry's data, not the entire archive, and will
     * stop at the end of the current entry's data if the number
     * to skip extends beyond that point.
     *
     * @param numToSkip The number of bytes to skip.
     * @return The actual number of bytes skipped.
     */
    public long
    skip( long numToSkip )
    throws IOException
    {
        // REVIEW
        // This is horribly inefficient, but it ensures that we
        // properly skip over bytes via the TarBuffer...
        //
        
        byte[] skipBuf = new byte[ 8 * 1024 ];
        long num = numToSkip;
        for ( ; num > 0 ; )
        {
            int numRead =
                this.read( skipBuf, 0,
                        ( num > skipBuf.length ? skipBuf.length : (int) num ) );
            
            if ( numRead == -1 )
                break;
            
            num -= numRead;
        }
        
        return ( numToSkip - num );
    }
    
    /**
     * Since we do not support marking just yet, we return false.
     *
     * @return False.
     */
    public boolean
    markSupported()
    {
        return false;
    }
    
    /**
     * Since we do not support marking just yet, we do nothing.
     *
     * @param markLimit The limit to mark.
     */
    public void
    mark( int markLimit )
    {
    }
    
    /**
     * Since we do not support marking just yet, we do nothing.
     */
    public void
    reset()
    {
    }
    
    /**
     * Get the number of bytes into the current TarEntry.
     * This method returns the number of bytes that have been read
     * from the current TarEntry's data.
     *
     * @returns The current entry offset.
     */
    
    public long
    getEntryPosition()
    {
        return this.entryOffset;
    }
    
    /**
     * Get the number of bytes into the stream we are currently at.
     * This method accounts for the blocking stream that tar uses,
     * so it represents the actual position in input stream, as
     * opposed to the place where the tar archive parsing is.
     *
     * @returns The current file pointer.
     */
    
    public long
    getStreamPosition()
    {
        return ( buffer.getBlockSize() * buffer.getCurrentBlockNum() )
        + buffer.getCurrentRecordNum();
    }
    
    /**
     * Get the next entry in this tar archive. This will skip
     * over any remaining data in the current entry, if there
     * is one, and place the input stream at the header of the
     * next entry, and read the header and instantiate a new
     * TarEntry from the header bytes and return that entry.
     * If there are no more entries in the archive, null will
     * be returned to indicate that the end of the archive has
     * been reached.
     *
     * @return The next TarEntry in the archive, or null.
     */
    public TarEntry
    getNextEntry()
    throws IOException
    {
        if ( this.hasHitEOF )
            return null;
        
        if ( this.currEntry != null )
        {
            long numToSkip = (this.entrySize - this.entryOffset);
            
            if ( this.debug )
                System.err.println
                ( "TarInputStream: SKIP currENTRY '"
                        + this.currEntry.getName() + "' SZ "
                        + this.entrySize + " OFF " + this.entryOffset
                        + "  skipping " + numToSkip + " bytes" );
            
            if ( numToSkip > 0 )
            {
                this.skip( numToSkip );
            }
            
            this.readBuf = null;
        }
        
        byte[] headerBuf = this.buffer.readRecord();
        
        if ( headerBuf == null )
        {
            if ( this.debug )
            {
                System.err.println( "READ NULL RECORD" );
            }
            
            this.hasHitEOF = true;
        }
        else if ( this.buffer.isEOFRecord( headerBuf ) )
        {
            if ( this.debug )
            {
                System.err.println( "READ EOF RECORD" );
            }
            
            this.hasHitEOF = true;
        }
        
        if ( this.hasHitEOF )
        {
            this.currEntry = null;
        }
        else
        {
            try {
                if ( this.eFactory == null )
                {
                    this.currEntry = new TarEntry( headerBuf );
                }
                else
                {
                    this.currEntry =
                        this.eFactory.createEntry( headerBuf );
                }
                
                if ( this.debug )
                    System.err.println
                    ( "TarInputStream: SET CURRENTRY '"
                            + this.currEntry.getName()
                            + "' size = " + this.currEntry.getSize() );
                
                this.entryOffset = 0;
                this.entrySize = this.currEntry.getSize();
            }
            catch ( InvalidHeaderException ex )
            {
                this.entrySize = 0;
                this.entryOffset = 0;
                this.currEntry = null;
                throw new InvalidHeaderException
                ( "bad header in block "
                        + this.buffer.getCurrentBlockNum()
                        + " record "
                        + this.buffer.getCurrentRecordNum()
                        + ", " + ex.getMessage() );
            }
        }
        
        return this.currEntry;
    }
    
    /**
     * Reads a byte from the current tar archive entry.
     *
     * This method simply calls read( byte[], int, int ).
     *
     * @return The byte read, or -1 at EOF.
     */
    public int
    read()
    throws IOException
    {
        int num = this.read( this.oneBuf, 0, 1 );
        if ( num == -1 )
            return num;
        else
            return (int) this.oneBuf[0];
    }
    
    /**
     * Reads bytes from the current tar archive entry.
     *
     * This method simply calls read( byte[], int, int ).
     *
     * @param buf The buffer into which to place bytes read.
     * @return The number of bytes read, or -1 at EOF.
     */
    public int
    read( byte[] buf )
    throws IOException
    {
        return this.read( buf, 0, buf.length );
    }
    
    /**
     * Reads bytes from the current tar archive entry.
     *
     * This method is aware of the boundaries of the current
     * entry in the archive and will deal with them as if they
     * were this stream's start and EOF.
     *
     * @param buf The buffer into which to place bytes read.
     * @param offset The offset at which to place bytes read.
     * @param numToRead The number of bytes to read.
     * @return The number of bytes read, or -1 at EOF.
     */
    public int
    read( byte[] buf, int offset, int numToRead )
    throws IOException
    {
        int totalRead = 0;
        
        if ( this.entryOffset >= this.entrySize )
            return -1;
        
        if ( (numToRead + this.entryOffset) > this.entrySize )
        {
            numToRead = (int) (this.entrySize - this.entryOffset);
        }
        
        if ( this.readBuf != null )
        {
            int sz = ( numToRead > this.readBuf.length )
            ? this.readBuf.length : numToRead;
            
            System.arraycopy( this.readBuf, 0, buf, offset, sz );
            
            if ( sz >= this.readBuf.length )
            {
                this.readBuf = null;
            }
            else
            {
                int newLen = this.readBuf.length - sz;
                byte[] newBuf = new byte[ newLen ];
                System.arraycopy( this.readBuf, sz, newBuf, 0, newLen );
                this.readBuf = newBuf;
            }
            
            totalRead += sz;
            numToRead -= sz;
            offset += sz;
        }
        
        for ( ; numToRead > 0 ; )
        {
            byte[] rec = this.buffer.readRecord();
            if ( rec == null )
            {
                // Unexpected EOF!
                throw new IOException
                ( "unexpected EOF with " + numToRead + " bytes unread" );
            }
            
            int sz = numToRead;
            int recLen = rec.length;
            
            if ( recLen > sz )
            {
                System.arraycopy( rec, 0, buf, offset, sz );
                this.readBuf = new byte[ recLen - sz ];
                System.arraycopy( rec, sz, this.readBuf, 0, recLen - sz );
            }
            else
            {
                sz = recLen;
                System.arraycopy( rec, 0, buf, offset, recLen );
            }
            
            totalRead += sz;
            numToRead -= sz;
            offset += sz;
        }
        
        this.entryOffset += totalRead;
        
        return totalRead;
    }
    
    /**
     * Copies the contents of the current tar archive entry directly into
     * an output stream.
     *
     * @param out The OutputStream into which to write the entry's data.
     */
    public void
    copyEntryContents( OutputStream out )
    throws IOException
    {
        byte[] buf = new byte[ 32 * 1024 ];
        
        for ( ; ; )
        {
            int numRead = this.read( buf, 0, buf.length );
            if ( numRead == -1 )
                break;
            out.write( buf, 0, numRead );
        }
    }
    
    /**
     * This interface is provided, with the method setEntryFactory(), to allow
     * the programmer to have their own TarEntry subclass instantiated for the
     * entries return from getNextEntry().
     */
    
    public
    interface	EntryFactory
    {
        public TarEntry
        createEntry( String name );
        
        public TarEntry
        createEntry( File path )
        throws InvalidHeaderException;
        
        public TarEntry
        createEntry( byte[] headerBuf )
        throws InvalidHeaderException;
    }
    
    public
    class		EntryAdapter
    implements	EntryFactory
    {
        public TarEntry
        createEntry( String name )
        {
            return new TarEntry( name );
        }
        
        public TarEntry
        createEntry( File path )
        throws InvalidHeaderException
        {
            return new TarEntry( path );
        }
        
        public TarEntry
        createEntry( byte[] headerBuf )
        throws InvalidHeaderException
        {
            return new TarEntry( headerBuf );
        }
    }
    
}
